Volcano Update from Archive

This report on the status of Kilauea volcanic activity, in addition to maps, photos, and Webcam images (available at http://hvo.wr.usgs.gov/activity/kilaueastatus.php), was prepared by the USGS Hawaiian Volcano Observatory (HVO). Hawai`i Volcanoes National Park status can be found at http://www.nps.gov/havo/ or 985-6000. All times are Hawai`i Standard Time.

Activity Summary: The eruption is 30 years old today with only a modest slowdown in activity. Kilauea continued to erupt at two locations: At the summit, DI deflation and descent of the lava lake surface continued. At Pu`u `O`o crater, glow was visible from the usual sources. To the southeast of Pu`u `O`o, a lava flow was active on the coastal plain and was entering the ocean at several locations along the flow front. Seismic tremor levels were low and gas emissions were elevated.

Recent Observations at Kilauea summit: The summit tiltmeter network continued recording DI deflation totaling almost 5 microradians by this morning. The lava lake surface rose and fell (rise/fall events) during most of yesterday before resuming its descent early this morning. Because of the low lava level, veneer on the walls of the conduit started peeling off and falling into the lake with the first big chunk falling in around 6 am yesterday and several smaller pieces joining it in the lake during the day. The most recent (preliminary) sulfur dioxide emission rate measurement was 400 tonnes/day on January 2, 2013; the relatively low emissions measured yesterday were typical of the reduced emissions observed during rise/fall events. A very small amount of ash-sized tephra (mostly fresh spatter bits and Pele's hair) was carried out of the vent in the gas plume and deposited on nearby surfaces.

Seismic tremor levels were low; the rockfalls mentioned above started a series of abrupt increases and decreases in seismic tremor amplitude (rise/fall events) that lasted from about 6 am yesterday through about 1 am this morning. Two earthquakes were strong enough to be located within Kilauea Volcano over the past 24 hours: 1 south of the summit caldera and 1 within the middle east rift zone (between Pu`u `O`o and Kupaianaha). The network of summit GPS receivers recorded minor extension and contractions that mimicked tilt inflation and deflation, respectively, but with no net change over the past 3 weeks

Background: The summit lava lake is deep within an ~160 m (520 ft) diameter cylindrical vent with nearly vertical sides inset within the east wall and floor of Halema`uma`u Crater. Its level has varied from about 25 m to more than 200 m (out of sight) below the floor of Halema`uma`u Crater. The vent has been mostly active since opening with a small explosive event on March 19, 2008. The surface level of the lava lake has remained below the inner ledge (~31 m or 100 ft below the floor of Halema`uma`u Crater on October 29, 2012) and has not risen above and flooded the ledge since October 28, 2012. The lake level responds to summit tilt changes with the lake receding during deflation and rising during inflation.

Recent Observations at the middle east rift zone vents: There was an apparent decrease in activity on the coastal plain. An approximately 1 km-wide (0.6 mi wide) lava flow remained active on the coastal plain with scattered surface activity extending from mid-coastal plain to the coast and straddling the easternmost boundary of Hawai`i Volcanoes National Park; activity levels appeared to decrease over the past 24 hours, possibly due to the ongoing DI deflation. Webcams recorded weak ocean entry plumes yesterday and this morning suggesting that lava was sporadically entering the ocean at multiple locations.

HAZARD ALERT:Lava entering the ocean builds lava deltas. The lava delta and adjacent areas are some of the most hazardous areas on the flow field. Frequent delta/bench collapses give little warning, can produce explosions capable of throwing both dense and molten rocks hundreds of meters (yards) in all directions (inland as well as out to sea), and can produce damaging local waves. The steam plume produced by lava entering the ocean contains fine lava fragments and an assortment of acid droplets that can be harmful to your health. The rapidly changing conditions near the ocean entry have been responsible for many injuries and a few deaths.

The tiltmeter on the north flank of Pu`u `O`o cone recorded continued DI deflation totaling about 4 microradians as of this morning. Within Pu`u `O`o crater, glow was observed from the usual sources. Seismic tremor levels near Pu`u `O`o remained low. The most recent (preliminary) sulfur dioxide emission rate measurement was 300 tonnes/day on January 2, 2013, from all east rift zone sources.

Background: The eruption in Kilauea's middle east rift zone started with a fissure eruption on January 3, 1983, and continued with few interruptions at Pu`u `O`o Cone, or temporarily from vents within a few kilometers to the east or west. A fissure eruption on the upper east flank of Pu`u `O`o Cone on Sept. 21, 2011, drained the lava lakes and fed a lava flow that advanced southeast through the abandoned Royal Gardens subdivision to the ocean within Hawai`i Volcanoes National Park in early December 2011. Since late December 2011, the flows have remained intermittently active on the pali and the coastal plain and finally re-entered the ocean starting on November 24, 2012. In general, activity waxes with inflation and wanes with deflation.

Hazard Summary:East rift vents and flow field - near-vent areas could erupt or collapse without warning with spatter and/or ash being wafted within the gas plume; potentially-lethal concentrations of sulfur dioxide gas may be present within 1 km downwind of vent areas. All recently active lava flows are within Hawai`i Volcanoes National Park, adjacent State land managed by the Department of Land and Natural Resources, and private property; the lava flows do not pose a hazard to any structures not already within the County-declared mandatory evacuation zone. Lava deltas, which can collapse into the ocean without warning, are extremely hazardous and should be avoided (see HAZARD ALERT above). Kilauea Crater - ash and Pele's hair can be carried several kilometers downwind; potentially-lethal concentrations of sulfur dioxide can be present within 1 km downwind.

Viewing Summary:East rift zone flow field - The active lava flows were within the closed-access Kahauale'a Natural Area Reserve (NAR) and the abandoned Royal Gardens subdivision and can only be viewed from the air. Under favorable weather conditions, these flows can be seen from the County Viewing Area at Kalapana (Lava hotline 961-8093). Pu`u `O`o Cone, the strip of coastal plain nearest the ocean, and Kilauea Crater - these areas are within Hawai`i Volcanoes National Park; Park access and viewing information can be found at http://www.nps.gov/havo/planyourvisit/lava2.htm.

Additional Information:

For a definition of volcano alert levels and aviation color codes: http://volcanoes.usgs.gov/activity/alertsystem/index.php

Maps, photos, Webcam views, and other information about Kilauea Volcano are available at http://volcanoes.usgs.gov/hvo/activity/kilaueastatus.php. A daily update summary is available by phone at (808) 967-8862.

A map with details of earthquakes located within the past two weeks can be found at http://hvo.wr.usgs.gov/seismic/volcweb/earthquakes/

HVO Contact Information:

askHVO@usgs.gov

Definitions of Terms Used:

DI tilt event: DI is an abbreviation for 'deflation-inflation' and describes a geophysical event of uncertain volcanic significance. DI events are recorded by tiltmeters at Kilauea summit as an abrupt deflation of up to a few microradians in magnitude lasting several hours (weak DI events) to 2-3 days (strong DI events) followed by an abrupt inflation of approximately equal magnitude. The tilt events are usually accompanied by an increase in summit tremor during the deflation phase. A careful analysis of these events suggests that they may be related to changes in magma supply to a storage reservoir at less than 1 km depth, just east of Halema`uma`u crater. Usually, though not always, these changes propagate through the magma conduit from the summit to the east rift eruption site, as many of the DI events at Kilauea summit are also recorded at a tiltmeter at Pu`u `O`o delayed by several hours. DI events often correlate with lava pulses and/or pauses in the eruption at the Pu`u `O`o/Peace Day vents.

fill-and-drain, rise/fall cycles or high lava stands: one of the cyclical behaviors exhibited by the summit lava lake. A cycle starts with a rise in lava level, a decrease in summit tremor amplitude, and a small decrease in tilt. After a period of minutes to hours, the lava will abruptly drain back to its previous level, seismic tremor amplitude will increase for a short time (a seismic tremor burst), and summit tilt will return to its previous level. Although not measured continuously, spot checks of gas emissions demonstrate that far less gas is released during the high lava stand than during its draining phase suggesting that, during the high lava stand, lava is puffed up with gas trapped by crusts on the lava surface; the gas plume will also get thin and wispy during these cycles returning to more robustness afterward.

perched lava lake: a lava lake within a rim that is progressively built up by overflows of lava that have cooled and solidified. The most recent example of a perched lava lake is currently active within Pu`u `O`o maintaining a rim standing several meters (yards) above the crater floor. In many ways, a perched lava lake resembles an above-ground swimming pool. Overflows from the pond add layers to the surrounding crater floor building it higher; the overflows also build up the perched lake rim, continually keeping the lake rim raised above the floor.

mauka, makai: Hawaiian terms for directions relative to the coast - makai or ma kai (toward the coast) and mauka or ma uka (toward the highlands or away from the coast).

pali: Hawaiian term for cliff or precipice.

composite seismic events: is a seismic signal with multiple distinct phases that has been recorded frequently at HVO from the Halema`uma`u Overlook vent area since its explosive opening in March, 2008. For the composite events recorded at Halema`uma`u, we typically see an initial high frequency vibration lasting for a few seconds that have been correlated with rockfalls. This is followed by about 30 seconds of a long-period (LP) oscillation with an approximately 2- to 3-second period. The final phase of the signal is several minutes of a very-long-period (VLP) oscillation with an approximately 25- to 30-second period. The LP signals are interpreted to be from the uppermost portion of the conduit and VLP signals are interpreted to be fluid passing through a deep constriction in the conduit through which lava rises to the pond surface we see in the webcam.

Halema`uma`u Overlook vent: has been difficult to describe concisely. The vent is actually a pit, or crater, in the floor of the larger Halema`uma`u Crater in the floor of the larger Kilauea caldera or crater - a crater within a crater within a crater. It is easiest to describe as a pit inset within the floor of a crater within a caldera. The pit is about 140 m (460 ft) in diameter at the Halema`uma`u Crater floor, is about 50 m in diameter at the pit floor, and is about 200 m (660 ft) deep. As of November, 2009, a lava pond surface has been visible in a hole in the floor of this pit.

glow: light from an unseen source; indirect light.

incandescence: the production of visible light from a hot surface. The term also refers to the light emitted from a hot surface. The color of the light is related to surface temperature. Some surfaces can display dull red incandescence at temperatures as low as 430 degrees Centigrade (806 degrees Fahrenheit). By contrast, molten lava displays bright orange to orange-yellow light from surfaces that are hotter than 900 degrees C (1,650 degrees F).